This invention relates to the refining of spindle oils, and particularly to the hydroprocessing of spindle oils.
Spindle oils are relatively high boiling fractions of crude oils and the like and are comparable to heavy atmospheric gas oils. The typical spindle oil boils in the range of about 500.degree. to 950.degree. F. (260.degree. to 510.degree. C.), with the initial boiling point usually being in the range of 500.degree. to 600.degree. F. (260.degree. to 316.degree. C.) and the end point in the range of 850.degree. to 950.degree. F. (454.degree. to 510.degree. C.).
In some instances, it is desirable in a refinery to reduce the pour point of a spindle oil without decreasing its viscosity. For example, if it is desired to reduce the pour point of a fuel oil without affecting its viscosity, one possible method is to use a spindle oil of comparable viscosity but of reduced pour point as a "cutter stock". Unfortunately, most spindle oils themselves have a relatively high pour point, and, if such oils are refined to reduce the pour point, there is a danger that the viscosity will be reduced as well.
It is a specific object of the invention to provide a process for treating a spindle oil for pour point reduction with minimum degradation of the viscosity to provide a blending stock for fuel oils. It is yet another object of the invention to achieve the foregoing while also reducing the nitrogen and sulfur contents of the spindle oil.